ID Keys

Protobranchia (500 - 5000m)

Shell height greater than or equal to length, subcircular to trigonal [c1, c2, c3], ligament internal in an anteriorly directed (opisthodetic) chondrophore [Nuculoidea & Pristiglomoidea]
Go to #2
Shell longer than high, frequently subrostrate or rostrate, [c4, c5, c6] ligament internal in a shallow resilifer or external. [Nuculanoidea]
Go to #9
Shell subcircular or obliquely oval, hinge with few posterior teeth subparallel to hinge plate [c7].[Pristiglomatoidea]
Go to #3
Shell triangular to subovate, hinge with numerous, prominent erect teeth [c.8] [Nuculoidea]
Go to #4
Shell obliquely oval [c9]
Pristigloma alba
Shell subcircular [c10]
Pristigloma nitens
Internal margin denticulate [c11]
Go to #5
Internal margin smooth [c12]
Go to #6
Triangular distinctly higher than long [c13], marked decussate sculpture, commarginal ridges becoming stronger towards margin. (bathyal)
Nucula tumidula
Shell subovate [c14], prominent larval shell, cancellate sculpture
Nucula atacellana
Shells distinctly higher than long, triangular or rhomboidal
Go to #7
Shells longer than high subtriangular or subovate
Go to #8
Shell triangular anterior and posterior equally inclined [c15].
Brevinucula verrilli
Shell rhomboidal, umbos inflated [c16].
Ennucula corticata
Shell subovate, posterior truncated [c17], surface microscopically granular [c18]
Ennucula granulosa
Shell subovate, anterior slope subacute [c19]
Ennucula corbuloides
Hinge teeth few, elongate, subparallel with hinge plate [c20].
Go to #10
Hinge teeth pointed erect
Go to #11
Shell elliptical [c21]
Lametila abyssorum
Shell elliptical [c21]
Silicula fragilis
Shells subrostrate with a posterior ventral sinus
Go to #12
Shells rostrate or subovate to oval
Go to #16
Shells with a sharply pointed dorsally situated posterior, ligament both interior and exterior, gut loop multi-coiled.
Go to #13
Shells with a pointed, medially or downwardly angled posterior, ligament interior, gut loop simple or multi-coiled.
Go to #14
Posterior much deeper than anterior, posterior below rostrum bulging.
Bathyspinula subexcisa
Posterior a little deeper than anterior, sulcus below rostrum weak.
Bathyspinula filatovae
Rostrum blunt
Go to #15
Rostrum acute. Posterior dorsal margin sloping (bathyal)
Ledella messanensis
Shell thick becoming tumid, sculpture of fine commarginal ridges.
Ledella ultima
Shells normal thickness, sculpture of weak radial and commarginal ridges, periostracum pustulose.
Ledella pustulosa
Minute (<1.5mm), rounded tumid shells
Go to #17
Shells ovate to rostrate
Go to #18
Outline elliptical with commarginal ridges at margins, teeth prominent
Microgloma pusilla
Outline subcircular (southern, bathyal)
Microgloma tumidula
External ligament visible close to beaks
Go to #19
Ligament internal not visible in joined valves.
Go to #21
Shell oblong, posterior broad, roundly truncated
Malletia johnsoni
Shell subovate to elliptical, posterior pointed
Go to #20
Subovate, robust shells with commarginal ridges
Neilonella latior
Elliptical, fragile smooth shells
Katadesmia cuneata
Robust, narrowly rostrate with prominent commarginal sculpture
Saccella commutata
Thin shells with weak sculpture, subovate to oblong.